Re: [CF-metadata] Units: degrees - COARDS/CF Convention

[Jonathan Gregory]

Dear Glenn

I too agree with your interpretation. COARDS and CF disallow degree for lat
and lon, but degree is allowed for some other quantities in the standard name
table e.g. grid_latitude and grid_longitude (for a rotated-pole system) have
units of degree.

I agree with Roy that quantities which are distinguished by according to
either magnetic or true bearing should have that distinction indicated in CF
by semantics i.e. standard_name, not by units.

Best wishes

Jonathan
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Re: [CF-metadata] Units: degrees - COARDS/CF Convention

[Lowry, Roy K.]

Dear All,

Reading this reminds me of an issue I need to address locally.  We have units 
'Degrees magnetic' and 'Degrees true' in our data system (many current meters 
are calibrated to magnetic and subsequently corrected to true).  The local 
approach I am trying to take is to move the semantics to the parameter 
description (Standard Name 'equivalent').  However, I guess I'm not alone in 
needing to provide labels to data in both co-ordinate systems, so agreeing a 
policy on how this situation is handled in CF could be helpful.

Cheers, Roy.

From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On 
Behalf Of Comiskey, Glenn [g.comis...@geos.com]
Sent: 14 July 2011 15:48
To: cf-metadata@cgd.ucar.edu
Subject: [CF-metadata] Units: degrees - COARDS/CF Convention

Hi,

The use of the variable unit value "degrees" would appear to discount a data 
set from being both COARDS and CF compliant, at least according to the CF 
conventions document, i.e. v1.5, section 3.1 states "The COARDS convention 
prohibits the unit "degrees" altogether" while also stating "this unit is not 
forbidden by the CF convention". Is this in fact true?

The COARDS convention does indeed state, when refering to UDUNITS, "names 
therein...will be regarded as acceptable unit names for this standard with the 
following additions and deletions: "degrees" - deleted". However, it then goes 
on to say "The unit "degrees" creates ambiguities when attempting to 
differentiate longitude and latitude coordinate variables; files must use 
"degrees_east"...and "degrees_north"".

Is it not a case that the COARDS convention is disallowing the use of the 
"degrees" value simply for coordinate variables, and subsequently mandating the 
use of "degrees_east" and "degrees_north", to remove any potential ambiguity 
with regards to the position the data relates, i.e. COARDS requires 
"degrees_east" and "degrees_north" for coordinates variables, but allows uses 
of "degrees" for a data variable such wind direction (NOTE: I am aware that the 
CF standard canonical unit is "degree").

Is there some convention (pun intended :-) to interpretating the COARDS 
convention as meaning that "degrees" is prohibited, period?

Kind regards,

Glenn Comiskey
Data System Administrator

Fugro Global Environment & Ocean Sciences
Fugro House, Hithercroft Road
Wallingford, Oxfordshire OX10 9RB, UK
Registration No: 2985431 / VAT No: GB 655475606

Tel: +44 (0) 1491 820500 (Switchboard) / Tel: +44 (0) 1491 820559 (Direct) / 
Fax: +44 (0) 1491 820599
E-mail: g.comis...@geos.com<mailto:g.comiskey@g.comis...@geos.com> / Website: 
www.geos.com<http://www.geos.com/>

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Re: [CF-metadata] Units: degrees - COARDS/CF Convention

[John Caron]

On 7/14/2011 8:48 AM, Comiskey, Glenn wrote:

Hi,
The use of the variable unit value "degrees" would appear to discount 
a data set from being both COARDS and CF compliant, at least according 
to the CF conventions document, i.e. v1.5, section 3.1 states "The 
COARDS convention prohibits the unit "degrees" altogether" while also 
stating "this unit is not forbidden by the CF convention". Is this in 
fact true?
The COARDS convention does indeed state, when refering to UDUNITS, 
"names therein...will be regarded as acceptable unit names for this 
standard with the following additions and deletions: "degrees" - 
deleted". However, it then goes on to say "The unit "degrees" creates 
ambiguities when attempting to differentiate longitude and latitude 
coordinate variables; files must use "degrees_east"...and 
"degrees_north"".
Is it not a case that the COARDS convention is disallowing the use of 
the "degrees" value simply for coordinate variables, and subsequently 
mandating the use of "degrees_east" and "degrees_north", to remove any 
potential ambiguity with regards to the position the data relates, 
i.e. COARDS requires "degrees_east" and "degrees_north" for 
coordinates variables, but allows uses of "degrees" for a data 
variable such wind direction (NOTE: I am aware that the CF standard 
canonical unit is "degree").
Is there some convention (pun intended :-) to interpretating the 
COARDS convention as meaning that "degrees" is prohibited, period?


Hi glenn:

"degrees" is a valid udunit for things like wind direction. It is not 
allowed as a unit for lat or lon, period. I think that is how you are 
interpreting it above.


john



Kind regards,
Glenn Comiskey
Data System Administrator
Fugro Global Environment & Ocean Sciences
Fugro House, Hithercroft Road
Wallingford, Oxfordshire OX10 9RB, UK
Registration No: 2985431 / VAT No: GB 655475606
Tel: +44 (0) 1491 820500 (Switchboard) / Tel: +44 (0) 1491 820559 
(Direct) / Fax: +44 (0) 1491 820599
E-mail: _g.comiskey@geos.com_ / 
Website: _www.geos.com_ 

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[CF-metadata] Units: degrees - COARDS/CF Convention

[Comiskey, Glenn]

Hi,
 
The use of the variable unit value "degrees" would appear to discount a
data set from being both COARDS and CF compliant, at least according to
the CF conventions document, i.e. v1.5, section 3.1 states "The COARDS
convention prohibits the unit "degrees" altogether" while also stating
"this unit is not forbidden by the CF convention". Is this in fact true?
 
The COARDS convention does indeed state, when refering to UDUNITS,
"names therein...will be regarded as acceptable unit names for this
standard with the following additions and deletions: "degrees" -
deleted". However, it then goes on to say "The unit "degrees" creates
ambiguities when attempting to differentiate longitude and latitude
coordinate variables; files must use "degrees_east"...and
"degrees_north"".
 
Is it not a case that the COARDS convention is disallowing the use of
the "degrees" value simply for coordinate variables, and subsequently
mandating the use of "degrees_east" and "degrees_north", to remove any
potential ambiguity with regards to the position the data relates, i.e.
COARDS requires "degrees_east" and "degrees_north" for coordinates
variables, but allows uses of "degrees" for a data variable such wind
direction (NOTE: I am aware that the CF standard canonical unit is
"degree").
 
Is there some convention (pun intended :-) to interpretating the COARDS
convention as meaning that "degrees" is prohibited, period?
 
Kind regards,
 
Glenn Comiskey
Data System Administrator
 
Fugro Global Environment & Ocean Sciences
Fugro House, Hithercroft Road
Wallingford, Oxfordshire OX10 9RB, UK
Registration No: 2985431 / VAT No: GB 655475606
 
Tel: +44 (0) 1491 820500 (Switchboard) / Tel: +44 (0) 1491 820559
(Direct) / Fax: +44 (0) 1491 820599
E-mail: g.comis...@geos.com   /
Website: www.geos.com  
 
Please note:

*   
The information contained in this message is privileged and
confidential and intended only for the use of the addresses.  If you are
not the intended recipient you should not read, copy, distribute or
otherwise use the information;
*   
Fugro Global Environment & Ocean Sciences accepts no
responsibility for loss or damage of any kind arising from the use of
this message;
*   
If you have received this message in error, please note the
sender immediately and delete the message.


 
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